[PATCH] BLOCK: Dissociate generic_writepages() from mpage stuff [try #6]
[linux-2.6.git] / include / linux / writeback.h
1 /*
2  * include/linux/writeback.h.
3  */
4 #ifndef WRITEBACK_H
5 #define WRITEBACK_H
6
7 struct backing_dev_info;
8
9 extern spinlock_t inode_lock;
10 extern struct list_head inode_in_use;
11 extern struct list_head inode_unused;
12
13 /*
14  * Yes, writeback.h requires sched.h
15  * No, sched.h is not included from here.
16  */
17 static inline int task_is_pdflush(struct task_struct *task)
18 {
19         return task->flags & PF_FLUSHER;
20 }
21
22 #define current_is_pdflush()    task_is_pdflush(current)
23
24 /*
25  * fs/fs-writeback.c
26  */
27 enum writeback_sync_modes {
28         WB_SYNC_NONE,   /* Don't wait on anything */
29         WB_SYNC_ALL,    /* Wait on every mapping */
30         WB_SYNC_HOLD,   /* Hold the inode on sb_dirty for sys_sync() */
31 };
32
33 /*
34  * A control structure which tells the writeback code what to do.  These are
35  * always on the stack, and hence need no locking.  They are always initialised
36  * in a manner such that unspecified fields are set to zero.
37  */
38 struct writeback_control {
39         struct backing_dev_info *bdi;   /* If !NULL, only write back this
40                                            queue */
41         enum writeback_sync_modes sync_mode;
42         unsigned long *older_than_this; /* If !NULL, only write back inodes
43                                            older than this */
44         long nr_to_write;               /* Write this many pages, and decrement
45                                            this for each page written */
46         long pages_skipped;             /* Pages which were not written */
47
48         /*
49          * For a_ops->writepages(): is start or end are non-zero then this is
50          * a hint that the filesystem need only write out the pages inside that
51          * byterange.  The byte at `end' is included in the writeout request.
52          */
53         loff_t range_start;
54         loff_t range_end;
55
56         unsigned nonblocking:1;         /* Don't get stuck on request queues */
57         unsigned encountered_congestion:1; /* An output: a queue is full */
58         unsigned for_kupdate:1;         /* A kupdate writeback */
59         unsigned for_reclaim:1;         /* Invoked from the page allocator */
60         unsigned for_writepages:1;      /* This is a writepages() call */
61         unsigned range_cyclic:1;        /* range_start is cyclic */
62 };
63
64 /*
65  * fs/fs-writeback.c
66  */     
67 void writeback_inodes(struct writeback_control *wbc);
68 void wake_up_inode(struct inode *inode);
69 int inode_wait(void *);
70 void sync_inodes_sb(struct super_block *, int wait);
71 void sync_inodes(int wait);
72
73 /* writeback.h requires fs.h; it, too, is not included from here. */
74 static inline void wait_on_inode(struct inode *inode)
75 {
76         might_sleep();
77         wait_on_bit(&inode->i_state, __I_LOCK, inode_wait,
78                                                         TASK_UNINTERRUPTIBLE);
79 }
80
81 /*
82  * mm/page-writeback.c
83  */
84 int wakeup_pdflush(long nr_pages);
85 void laptop_io_completion(void);
86 void laptop_sync_completion(void);
87 void throttle_vm_writeout(void);
88 void writeback_congestion_end(void);
89
90 /* These are exported to sysctl. */
91 extern int dirty_background_ratio;
92 extern int vm_dirty_ratio;
93 extern int dirty_writeback_interval;
94 extern int dirty_expire_interval;
95 extern int block_dump;
96 extern int laptop_mode;
97
98 struct ctl_table;
99 struct file;
100 int dirty_writeback_centisecs_handler(struct ctl_table *, int, struct file *,
101                                       void __user *, size_t *, loff_t *);
102
103 void page_writeback_init(void);
104 void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
105                                         unsigned long nr_pages_dirtied);
106
107 static inline void
108 balance_dirty_pages_ratelimited(struct address_space *mapping)
109 {
110         balance_dirty_pages_ratelimited_nr(mapping, 1);
111 }
112
113 int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
114 extern int generic_writepages(struct address_space *mapping,
115                               struct writeback_control *wbc);
116 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
117 int sync_page_range(struct inode *inode, struct address_space *mapping,
118                         loff_t pos, loff_t count);
119 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
120                            loff_t pos, loff_t count);
121 void set_page_dirty_balance(struct page *page);
122 void writeback_set_ratelimit(void);
123
124 /* pdflush.c */
125 extern int nr_pdflush_threads;  /* Global so it can be exported to sysctl
126                                    read-only. */
127
128
129 #endif          /* WRITEBACK_H */